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"Good to see that sufficient progress has been made in Brexit negotiations in the areas of citizens' rights, the financial aspects and the (Northern) Irish border," Dutch prime minister Mark Rutte said on Twitter.

"I have told Theresa May I am happy that we can proceed to the next phase in which we can discuss our future relationship," he added.

Spain's Mariano Rajoy also took to Twitter to express his endorsement.

"The agreements reached between the European Union and the United Kingdom are good news and will minimise the costs of Brexit. I congratulate Michel Barnier and Theresa May for their efforts on everyone's behalf," he tweeted.

"Today's progress in EU/UK Brexit negotiations is good news. Expect EUCO [European Council] can conclude 'sufficient progress' next week. Then we are ready to move to phase 2," Denmark's prime minister Lars Lokke Rasmussen said in a tweet.

Belgium's Charles Michel called the deal "an important step".

"An intelligent Brexit deal is in interest of our citizens and companies. #UK is and forever will be our neighbour. But our job is not done yet!," he warned.

Juri Ratas, prime minister of Estonia, that holds the EU's rotating presidency, tweeted: "Glad for today's #brexitdeal that reassures rights for our citizens and businesses in UK. Barnier and his team have stood up for EU27 while grateful for PM May and UK Davis for compromises."

"A positive agreement was reached on Brexit. I am sure that the EU Council will launch talks. Italy has never stood for the 'no deal'," Italy's prime minister Paolo Gentiloni said Friday.

The mood in Germany was less celebratory and officials warned of the difficult road ahead.

Berlin hailed the agreement as "a step forward".

"I think everyone understands that there is still much work for negotiators to do even if the European Council decides to move into phase two of Brexit negotiations," German government spokesman Steffen Seibert said at a regular press conference of Friday (8 December).

He added that the second phase would be "highly complex".

The deal hung by a thread after British prime minister Theresa May on Monday (4 December) needed to rush back to London for an after the 11th-hour consultation with her Northern Irish unionist allies about the Irish border part of the deal.

"It is a great mess, nobody knows if [Theresa] May will come back, or when," MEP Gabriele Zimmer, a member of the European Parliament's Brexit steering group told this website at Thursday lunchtime.

But by Friday dawn May pulled through with the agreement.

Barnier told reporters at a press conference the agreed text is "precise and detailed". He warned however that more work remains "on a number of issues."

EU council president Donald Tusk echoed the same, saying the "most difficult challenge is still ahead".

"To negotiate a transition arrangement and the framework for our future relationship, we have de facto less than a year," he said.